Galileo said that objects will drop to the ground at the same speed, no matter their weight. A hammer and a feather should land at the same time. However, objects on earth are affected by air resistance, causing the feather to float around. In July 1971, Apollo 15 astronaut David Scott put Galileoâ€™s theory of gravitational pull to the test on the moon. Push play or go to YouTube. Link to NASA page. -via Grow-A-Brain